Asked Deej today what, exactly, it is that combat troopers even do now that we don't just conquer planets and force them to join the First Order anymore.
She said, "Demonstrations, mostly."
"Demonstrations of power? Like, you murder the most powerful people in front of their citizens or intimidate them with your superior fire power until they surrender to us?"
"Oh, no. Nothing like that. We mostly do a lot of marching, spar with each other, do heavily-choreographed flyovers with TIE fighters, that sort of thing. Then they finish it all off with a motivational speech from one of our officers about how peace and order can be achieved through proper education. That usually impresses the locals enough that they want to open their own branch of the Academy."
"So. . .if we're slowly taking over the galaxy by winning the hearts and minds of its inhabitants. . .why do we even teach combat training anymore?"
"I asked Captain Phasma the same thing. Her answer was basically 'Shut up. It's fun.'"